1. Field of the Invention
This invention relates generally to the field of rotary head drums for magnetic tape recording and/or playback devices such as video tape recorders. More particularly, this invention relates to a helical scan rotary head drum having a reduced height which is advantageous for miniaturization of video cassette recorders (VCR).
2. Background of the Invention
In a conventional video cassette recorder (VCR), a S/R helical scan type rotary head drum is used. It carries a transducer for recording and/or reproducing a video signal on a magnetic tape. It is mounted on a VCR chassis in an inclined position. The rotary head drum has a lower stationary (or fixed) drum and an upper rotary drum rotatably mounted on an axis of the lower stationary drum. The lower stationary drum has an inclined tape lead on its outer surface for guiding a magnetic tape. The upper rotary drum has, for example, a pair of transducers at its lower edge. The transducers protrude from the outer surface of the drums by a predetermined amount. As the rotary head drum rotates, slanted tracks are provided on the magnetic tape.
A tape loading mechanism having loading guides and inclined guides draws the magnetic tape from a tape cassette so that the rotary head drum is wrapped with the magnetic tape helically. As the rotary head drum rotates and the transducers scan the magnetic tape, slanted tracks are provided on the magnetic tape.
This type of conventional VCR has several disadvantages as follows. Since the rotary head drum is mounted on the chassis in an inclined position, the vertical height (distance between the highest point and the lowest point of the drum) required to enclose the drum is greater than if the drum were mounted perpendicular to the chassis. Therefore, a VCR using such a drum is limited in height by this vertical height. In addition, during a so-called M loading operation where a tape cassette is positioned near the rotary head drum, the rotary head drum cannot be put into the front opening of the tape cassette due to the height of the rotary head drum. Therefore, the minimum depth of the VCR is limited as is the minimum size of the VCR.
On the other hand, a different type of VCR has been designed. In that VCR, a rotary head drum is mounted vertically on a VCR chassis to make the VCR size smaller. However, it requires more than four inclined tape guides in a tape path. Compared with a helical scan type VCR, it needs more tape guides and adjustment of the tape guides is more complex.